A construction machine or the like includes an oil-pressure pump, and the oil-pressure pump ejects pressure oil when an operating lever or the like is operated. The ejected pressure oil is introduced to an oil-pressure actuator, such as an oil-pressure cylinder, to operate the oil-pressure actuator. An arm, a boom, and the like operate by the operation of the oil-pressure actuator. The oil-pressure pump is coupled to an engine and an electric motor through a rotating shaft and is rotated by the engine and the electric motor. As the construction machine configured as above, for example, a construction machine of PTL 1 is known.
In the construction machine of PTL 1, the engine is controlled by a control device such that the revolution speed of the engine becomes a revolution speed command. However, the revolution speed of the engine decreases when a load is applied to the oil-pressure pump, such as when the oil-pressure pump drives the oil-pressure actuator. When the revolution speed of the engine decreases, and this increases a deviation between the revolution speed of the engine and the revolution speed command, the control device causes the electric motor to assist the engine. Thus, the control device maintains the revolution speed of the engine (specifically, the revolution speed command) constant.
In the construction machine of PTL 1, when a large load is applied to the oil-pressure pump, an upper limit of an absorbing torque of the oil-pressure pump is reduced. The upper limit of the absorbing torque is set in accordance with an engine revolution speed deviation ΔN (deviation between an actual revolution speed and a target revolution speed) based on a predetermined control characteristic.